It is a common problem in wireless communications that users situated relatively far from the base station that serves them are generally most susceptible to interference from neighboring base stations and to signal attenuation. As a consequence, such users may experience relatively low signal-to-interference-and-noise ratios (SINRs).
Below, we will refer to the relatively distant users as “cell-edge users” or as users with “poor geometry.” It will be understood that when one user is said to be more “distant” from the base station than another, what is meant does not depend solely on geographical distance, but also to susceptibility to other factors leading to attenuation and interference.
Various strategies may be used to keep the error rates at an acceptable level in the data received by such relatively distant users. Such strategies typically involve some sacrifice of spectral efficiency in order to keep error rates low. For example, coding rates may be reduced, or sub-channelization techniques may be employed to concentrate power in a limited portion of the full available frequency band.
It is typical of such strategies that they are implemented independently by the various base stations. However, coordination across cells or across sectors may improve efficiencies achieved with strategies such as sub-channelization. There remains a need for appropriate approaches to coordination of this kind.